Merge pull request #10190 from ktdreyer/doc-delete-pool

doc: more details for pool deletion

Reviewed-by: Brad Hubbard <bhubbard@redhat.com>
Reviewed-by: Kefu Chai <kchai@redhat.com>

doc/rados/operations/pools.rst

@@ -179,9 +179,22 @@ To delete a pool, execute::
 
 	
 If you created your own rulesets and rules for a pool you created,  you should
-consider removing them when you no longer need your pool.  If you created users
-with permissions strictly for a pool that no longer exists, you should consider
-deleting those users too.
+consider removing them when you no longer need your pool::
+
+	ceph osd pool get {pool-name} crush_ruleset
+
+If the ruleset was "123", for example, you can check the other pools like so::
+
+	ceph osd dump | grep "^pool" | grep "crush_ruleset 123"
+
+If no other pools use that custom ruleset, then it's safe to delete that
+ruleset from the cluster.
+
+If you created users with permissions strictly for a pool that no longer
+exists, you should consider deleting those users too::
+
+	ceph auth list | grep -C 5 {pool-name}
+	ceph auth del {user}
 
 
 Rename a Pool